Parallel Battery System with Differential Resistance
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Solution Overview
Problem
Conventional battery systems for vehicles with lead batteries and sub-batteries connected in parallel face issues with high degradation and reduced life due to uneven charging and discharging currents, leading to increased manufacturing costs and inefficient regenerative braking, which affects fuel efficiency.
Innovation Solution
A battery system where the sub-battery has a lower charging resistance than the lead battery, allowing it to charge with a larger current and store energy efficiently, thereby reducing degradation and improving fuel efficiency by balancing charging and discharging currents without the need for a DC/DC converter or complex circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lead battery and sub-battery are connected in parallel through a DC/DC converter, then the battery system can be charged by regenerative braking power, but the circuit construction becomes complicated and parts cost increases
Solution Approach 1:
The invention extracts and removes the DC/DC converter from the battery system, connecting the lead battery and sub-battery directly in parallel without complex voltage conversion circuitry. This simplifies the circuit construction while maintaining the ability to charge both batteries from regenerative braking power.
Solution Approach 2:
The invention introduces a control device as a simple mediator that manages power distribution between the lead battery, sub-battery, and vehicle loads based on their respective states of charge and power requirements, replacing the need for complex DC/DC conversion circuitry.
2Power
If a DC/DC converter is used to connect the lead battery and sub-battery, then power can be distributed between batteries, but power loss in the converter reduces charging power from regenerative braking
Solution Approach 1:
The DC/DC converter is completely removed from the system, eliminating its inherent power losses. The lead battery and sub-battery are connected directly in parallel, allowing regenerative braking power to charge both batteries simultaneously without conversion losses.
Solution Approach 2:
The battery system uses its own inherent characteristics (different internal resistances and voltage levels) to automatically distribute charging current between the lead battery and sub-battery, without requiring external active power conversion devices that would introduce losses.
3Reliability
If the lead battery is charged by regenerative braking power alone, then the battery voltage varies widely causing degradation, but adding a sub-battery through DC/DC converter increases manufacturing cost
Solution Approach 1:
The invention merges the lead battery and sub-battery into a unified parallel connection, allowing them to share the regenerative braking charging load. This combination stabilizes the voltage across both batteries, preventing the wide voltage variations that cause lead battery degradation, while avoiding the need for expensive DC/DC conversion equipment.
Solution Approach 2:
The invention changes the system configuration from a single battery or series connection to a parallel connection with different battery types, utilizing their different internal resistance characteristics to naturally balance the charging current distribution and stabilize voltage levels.
4Productivity
If a large current carrying capacity DC/DC converter is used for regenerative braking, then both batteries can be charged, but the parts cost of the DC/DC converter remarkably increases
Solution Approach 1:
The expensive high-current DC/DC converter is removed entirely. Instead, the lead battery and sub-battery are connected directly in parallel, allowing regenerative braking current to flow to both batteries simultaneously based on their natural electrical characteristics, eliminating the need for costly high-power conversion equipment.
Solution Approach 2:
The invention uses the natural electrical characteristics of the two different battery types as their own current distribution mechanism, copying the function of an active DC/DC converter through passive parallel connection and differential internal resistance, thereby avoiding the need for expensive active power electronics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The battery system effectively prolongs the life of the lead battery, improves charging efficiency, and enhances fuel efficiency by efficiently utilizing regenerative braking power, reducing the load on the engine and alternator, while maintaining a simple and cost-effective circuit design.
Implementation Method 1
a charging resistance r2 of the sub-battery is lower than a charging resistance r1 of the lead battery
Data Source
AI summary
In a battery system for a vehicle, a lead battery is connected in parallel to a sub-battery, and a charging resistance r2 of the sub-battery 2 is lower than a charging resistance r1 of the lead battery.